Fetal Neuroimaging by Transvaginal 3D Ultrasound and MRI

Abstract

ABSTRACT Three-dimensional (3D) ultrasound is one of the most attractive modality in the field of fetal ultrasound imaging. In multiplanar imaging of the brain structure, it is possible to demonstrate not only the sagittal and coronal sections but also the axial section of the brain, which cannot be demonstrated from parietal direction by a conventional 2D transvaginal sonography. Parallel slicing provides a tomographic visualization of internal morphology similar to MR imaging. Fetal neuroimaging with advanced 3D ultrasound technology is easy, noninvasive and reproducible methods. It produces not only comprehensible images but also objective imaging data. It has been controversial whether ultrasound or MRI is more practical and effective in prenatal assessment of fetal CNS abnormalities. In the assessment of enlarged ventricles, no significant difference between dedicated neurosonography and MRI in detection of intracranial structure. However, MRI is superior to ultrasound in evaluation of the brainstem, posterior fossa and cortical development especially in the late pregnancy. Meanwhile, transvaginal high-frequent 3D ultrasound has superiority to MRI in detection of intracranial calcification, vascular anatomy, intratumoral vascularity, bony structure. For CNS anomaly screening scan, ultrasound is no doubt the first modality, and once CNS abnormality is suspicious, after considering each advantage and disadvantage of transvaginal 3D ultrasound and MRI, it is suggested to use those different technologies according to what to be detected and evaluated in each abnormal CNS case. Of course, those two technologies should be utilized as alternatives and complementaries as well. In terms of fetal neurological function analysis, four-dimensional ultrasound research on fetal behavior have been launched in multicenters, and it will be greatly expected to elucidate relations between antenatal behavior and postnatal neurological prognosis.